A vehicle air-conditioning system disclosed in PTL 1 is configured that it is arranged in the front in a vehicle traveling direction, that an air blower, an evaporator, a heater core are housed in an air passage formed in an air-conditioning case, that an air mix door is provided to adjust a mixture ratio of the air that passes through the heater core and the air that bypasses the heater core, and that a defrost opening, a center vent opening, a side vent blowout opening, and a foot blowout opening are provided on a downstream side of this air mix door.
Then, in a foot mode, hot air flows out of a foot opening, the hot air is blown out of the defrost opening through a defrost port, and the hot air is blown out of a side vent opening through a side vent blowout port. Accordingly, fogging of windowpanes in the front and on right and left end sides in a vehicle cabin of a vehicle is prevented.
In addition, a vehicle air-conditioning system disclosed as another example in PTL 1 is configured by having: a def/vent mode door for switching between the center vent opening and the defrost opening; and a vent mode door for opening and closing the center vent opening.